Burn Angel reporting himself here to give his report about bugs. Again.
Going inside Mr. White's hideout while on the bike is not a problem. He's cool with you riding your bike around him. But don't you dare get off the bike while you're in his hideout, or he'll cause the end of the world. Quite literally.
This silly boy dissapears from the dungeon if you run away from him. 
Using either a firecracker or a smoke bomb on his encounter will despawn him from the map, thus making even his encounter not dangerous to the player, so there's absolutely not a single dangerous thing in the abomination dungeon. 
None of these bugs are really gamebreaking (although the Mr. White's hideout may make people lose unsaved progress), so it's okay to leave them be and fix them on v0.41.
(Gosh, me alone have made you release 0.40.4 and 0.40.5, haha)